Harvester Speed Control via Dual-Loop Feedback
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Solution Overview
Problem
Combine harvesters face inefficiencies and mechanical stress due to varying crop densities, leading to overloading, grain loss, and maintenance issues, as existing control systems based on threshing drum torque are inaccurate and delayed in responding to density changes.
Innovation Solution
A dual-loop control system with sensors measuring header and straw elevator drive torque, and a sensing pulley to detect drive belt tension, allowing for immediate adjustment of ground speed to maintain optimal crop flow, incorporating a static gain estimator to adjust control loop gains and account for varying conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the combine harvester drives at constant speed through the field, then the work rate is maximized, but the straw elevator becomes overloaded when encountering high crop density regions
Solution Approach 1:
The patent implements a feedback control system using sensors to detect crop density and feed rate, continuously adjusting the ground speed to maintain optimal harvesting conditions. The control system processes sensor signals and adjusts the combine's speed in real-time, preventing straw elevator overload while maximizing work rate.
Solution Approach 2:
The patent transitions from constant speed operation to dynamic speed adjustment. The ground speed is continuously varied based on real-time crop density detection, allowing the combine to adapt its operating parameters to match actual field conditions and prevent overloading.
2Productivity
If the combine harvester increases speed to maximize work rate, then productivity improves, but grain loss increases due to insufficient processing time
Solution Approach 1:
The feedback control system monitors feed rate and crop density, adjusting ground speed to maintain optimal processing capacity utilization. This ensures sufficient processing time is provided even at higher speeds, preventing grain loss while maximizing productivity.
Solution Approach 2:
The patent dynamically changes the ground speed parameter based on crop density and feed rate conditions. By adjusting this key parameter in real-time, the system optimizes the balance between productivity and grain loss prevention.
3Adaptability or versatility
If visual inspection by the driver is used to adjust speed, then some adaptation to crop density is achieved, but the response is insufficiently accurate and timely
Solution Approach 1:
The patent replaces manual visual inspection with automated sensor-based detection systems. Optical sensors, torque sensors, and feed rate monitors objectively measure crop density and feed conditions, providing precise data for control decisions without relying on driver perception.
Solution Approach 2:
The control system performs self-adjustment based on sensor feedback, automatically modifying ground speed without requiring continuous driver intervention. The system serves itself by monitoring its own operating parameters and making corrections to maintain optimal performance.
4Extent of automation
If existing control systems based on threshing drum torque are used, then some control is achieved, but the response is delayed and inaccurate due to the time lag for crop to reach the threshing drum
Solution Approach 1:
The patent measures crop density and feed rate at the header assembly, where crop enters the combine, rather than at the threshing drum. This preliminary measurement allows the control system to anticipate and respond to feed rate changes before they affect downstream processing, eliminating the time lag.
Solution Approach 2:
The patent introduces intermediate measurement points at the header assembly and straw elevator, which serve as early warning indicators of feed rate changes. These intermediary sensors provide advance notice of conditions that would otherwise only be detected later in the processing sequence.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This system provides accurate and immediate control of ground speed, reducing grain loss, fuel consumption, and mechanical stress, while maintaining operator comfort by detecting crop density changes near the header assembly, thus enhancing harvesting efficiency and reducing maintenance needs.
Implementation Method 1
A sensing pulley is provided for detecting drive belt tension
Data Source
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AI summary
Apparatus for controlling the speed of a combine harvester (10) comprises one or more sensors (48) each generating one or more signals (28, 36) that correspond during use of the combine harvester to variables of a harvesting process; a processor; and one or more control devices operatively connected in a feedback arrangement comprising two loops in a first of which a first said signal (28) corresponding to the ground speed of the combine harvester (10) is fed back as an input to a first said control device (42) that is capable of adjusting the said ground speed relative to a set value; and in a second of which the said first signal (28) is fed together with a second said signal (34) indicative of the flow rate of crop through the combine harvester to a second said control device (32) that generates as a third signal (31) the said set value, the third signal being input to the first said control device (42).